05.07.2009

Tankers are used to transport crude oil and refined products in waterborne trade. Ship carrying crude oil or refined products. The tankers can be used in either “clean” (light refined products such as gasoline and diesel fuel) or “dirty” (residual fuel and crude oil) trade. The tankers range in size from the small vessels used to transport refined products to huge crude carriers. Tanker sizes are expressed in terms of deadweight tons (dwt). The smallest tankers are General Purpose which range from 10 to 25,000 tons and the largest are 550,000 tons. These tankers are used to transport refined products. Tankers are unloaded/loaded at the jetties or the specially build piers. If a ship is equipped to carry several types of cargo simultaneously the ship is called a Parcel Tanker. A Shuttle Tanker is a tanker carrying oil from offshore fields to terminals. An oil tanker especially built for the transportation of refined oil products, often with inside painted/coated tanks, is called a Product Tanker.

Natural gas that contains no sulfur or sulfur compounds at all or in such small quantities that no processing is necessary for their removal in order that the gas may be used as a non-corrosive fuel.

One of the most important parts of gas processing involves the removal of sulfur and carbon dioxide. Because of the rotten smell provided by its sulfur content, this natural gas is called ‘sour gas’. This sulfur can be lethal to breathe and also very corrosive for pipelines or generation facilities. In addition, the sulfur that exists in the natural gas can be extracted and marketed on its own. Sulfur exists in natural gas as hydrogen sulfide (H2S), and the gas is usually considered sour if the hydrogen sulfide content exceeds 5.7 milligrams of H2S per cubic meter of natural gas. The process for removing hydrogen sulfide from sour gas is commonly referred to as sweetening the gas

In transporting gas from the production field to the end user, the demand fluctuates throughout the day, known as “diurnal swing”. The production field exports gas at a steady rate, but it is used variably throughout the day by customers (e.g. less during the night). Some of this swing capacity can be built into the production facilities and some can be provided by the national transmission system (all at a price of course).

Swing can be achieved by throttling the flowrate at a pressure reduction platform and thus using the flowlines from the field as storage. This is known as packing where rates into the flowlines exceed withdrawal rates, and then at times of high demand the pressure is allowed to fall which is known as drafting where rates into the pipeline are less than withdrawal

In other countries (besides Israel) gas is usually stored when demand is low in order to compensate for this, so that it can be used when demand is high.

Pipelines and equipment connecting the well or subsea system to a floating unit

These are the “leftover” gases at the end of a continuous chemical manufacturing process, that are neither product nor recyclable reactants, but are the result of various side reactions.

Tail gas = Residue gas from a sulfur recovery unit; any gas from a processing unittreated as residue

A steel rod that is used to make up the mechanical assembly between the surface and downhole components of a rod pumping system.

An oil or gas field identified by a discovery well, but not being produced or developed